U.S. patent number 8,020,645 [Application Number 12/858,949] was granted by the patent office on 2011-09-20 for method of fabricating polycrystalline diamond and a polycrystalline diamond compact.
This patent grant is currently assigned to US Synthetic Corporation. Invention is credited to Kenneth E. Bertagnolli, Debkumar Mukhopadhyay, Jiang Qian, Michael Vail, Jason Wiggins.
United States Patent |
8,020,645 |
Bertagnolli , et
al. |
September 20, 2011 |
Method of fabricating polycrystalline diamond and a polycrystalline
diamond compact
Abstract
Embodiments of the invention relate to polycrystalline diamond
("PCD") exhibiting enhanced diamond-to-diamond bonding. In an
embodiment, PCD includes a plurality of diamond grains defining a
plurality of interstitial regions. A metal-solvent catalyst
occupies at least a portion of the plurality of interstitial
regions. The plurality of diamond grains and the metal-solvent
catalyst collectively exhibit a coercivity of about 115 Oersteads
("Oe") or more and a specific magnetic saturation of about 15
Gausscm.sup.3/grams ("Gcm.sup.3/g") or less. Other embodiments are
directed to polycrystalline diamond compacts ("PDCs") employing
such PCD, methods of forming PCD and PDCs, and various applications
for such PCD and PDCs in rotary drill bits, bearing apparatuses,
and wire-drawing dies.
Inventors: |
Bertagnolli; Kenneth E.
(Riverton, UT), Qian; Jiang (Cedar Hills, UT), Wiggins;
Jason (Draper, UT), Vail; Michael (Genola, UT),
Mukhopadhyay; Debkumar (Sandy, UT) |
Assignee: |
US Synthetic Corporation (Orem,
UT)
|
Family
ID: |
41480456 |
Appl.
No.: |
12/858,949 |
Filed: |
August 18, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100307070 A1 |
Dec 9, 2010 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12244960 |
Oct 3, 2008 |
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Current U.S.
Class: |
175/434; 175/433;
51/309 |
Current CPC
Class: |
F16C
33/043 (20130101); E21B 10/567 (20130101); G01N
27/72 (20130101); C22C 26/00 (20130101); F16C
33/26 (20130101); G01N 27/80 (20130101); B21C
3/025 (20130101); B24D 18/0009 (20130101); C04B
37/001 (20130101); Y10T 428/24058 (20150115); F16C
2220/20 (20130101); C04B 2237/36 (20130101); C04B
2237/363 (20130101); Y10T 428/30 (20150115); F16C
2352/00 (20130101); Y10T 428/252 (20150115); F16C
2206/82 (20130101); Y10T 428/25 (20150115); F16C
2206/04 (20130101); F16C 17/04 (20130101); F16C
2240/48 (20130101); F16C 17/02 (20130101); F16C
2240/40 (20130101); Y10T 428/24997 (20150401) |
Current International
Class: |
E21B
10/46 (20060101) |
Field of
Search: |
;419/11,49 ;51/309 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0462955 |
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Dec 1991 |
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EP |
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121251 |
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Jun 1985 |
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JP |
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WO2004/106004 |
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Dec 2004 |
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WO |
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WO2006/099194 |
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Sep 2006 |
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WO |
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WO2007/020518 |
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Feb 2007 |
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WO |
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Primary Examiner: King; Roy
Assistant Examiner: Mai; Ngoclan
Attorney, Agent or Firm: Workman Nydegger
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser.
No. 12/244,960 filed on 3 Oct. 2008, the disclosure of which is
incorporated herein, in its entirety, by this reference.
Claims
The invention claimed is:
1. A method of forming a polycrystalline diamond compact,
comprising: enclosing a plurality of diamond particles that exhibit
an average particle size of about 30 .mu.m or less, and a cemented
carbide substrate including a metal-solvent catalyst therein in a
pressure transmitting medium to form a cell assembly; and
subjecting the cell assembly to a temperature of at least about
1400.degree. Celsius and a pressure in the pressure transmitting
medium of at least about 7.5 GPa to infiltrate the plurality of
diamond particles with a portion of the metal-solvent catalyst and
catalyze formation of a polycrystalline diamond table that bonds to
the cemented carbide substrate, wherein the polycrystalline diamond
table includes about 1 weight % to about 6 weight % of the
metal-solvent catalyst therein.
2. The method of claim 1 wherein subjecting the cell assembly to a
temperature of at least about 1400.degree. Celsius and a pressure
in the pressure transmitting medium of at least about 7.5 GPa
comprises subjecting the cell assembly to a pressure in the
pressure transmitting medium of at least about 8.0 GPa.
3. The method of claim 1 wherein subjecting the cell assembly to a
temperature of at least about 1400.degree. Celsius and a pressure
in the pressure transmitting medium of at least about 7.5 GPa
comprises subjecting the cell assembly to a pressure in the
pressure transmitting medium of at least about 9.0 GPa.
4. The method of claim 1 wherein subjecting the cell assembly to a
temperature of at least about 1400.degree. Celsius and a pressure
in the pressure transmitting medium of at least about 7.5 GPa
comprises subjecting the cell assembly to a pressure in the
pressure transmitting medium of at least about 10.0 GPa.
5. The method of claim 1 wherein the polycrystalline diamond table
exhibits a coercivity of about 115 Oe or more.
6. The method of claim 1 wherein the polycrystalline diamond table
exhibits a coercivity of about 115 Oe to about 250 Oe and a
specific magnetic saturation of about 5 Gcm.sup.3/g to about 15
Gcm.sup.3/g.
7. The method of claim 1 wherein the polycrystalline diamond table
exhibits a coercivity of about 130 Oe to about 160 Oe, a specific
magnetic saturation of about 10 Gcm.sup.3/g to about 15
Gcm.sup.3/g, and the metal-solvent catalyst is present in an amount
of about 3 weight % to about 6 weight %.
8. The method of claim 1 wherein the polycrystalline diamond table
comprises a plurality of diamond grains defining a plurality of
interstitial regions, the metal-solvent catalyst occupying at least
a portion of the plurality of interstitial regions.
9. The method of claim 1 wherein the amount of the metal-solvent
catalyst present in the polycrystalline diamond table is about 3
weight % to about 6 weight %.
10. The method of claim 1 wherein the amount of the metal-solvent
catalyst present in the polycrystalline diamond table is about 1
weight % to about 3 weight %.
11. The method of claim 1 wherein the amount of the metal-solvent
catalyst present in the polycrystalline diamond is about 1 weight
%.
12. The method of claim 1 wherein the cemented carbide substrate
comprises chromium carbide.
13. The method of claim 1 wherein the average particle size of the
plurality of diamond particles is about 20 .mu.m or less.
14. The method of claim 1 wherein the average particle size of the
plurality of diamond particles is about 10 .mu.m or less.
15. The method of claim 1 wherein subjecting the cell assembly to a
temperature of at least about 1400.degree. Celsius and a pressure
in the pressure transmitting medium of at least about 7.5 GPa
comprises selecting the pressure so that the polycrystalline
diamond exhibits a residual principal stress on a working surface
thereof of about -345 MPa to about 0 MPa.
16. The method of claim 1 wherein the polycrystalline diamond table
exhibits a thermal stability of at least about 1300 m as determined
by a distance cut, prior to failure, in a vertical lathe test.
17. The method of claim 1 wherein the pressure transmitting medium
comprises a gasket material, and wherein the cell assembly is a
cubic cell assembly.
18. A method of fabricating a polycrystalline diamond compact,
comprising: enclosing a plurality of diamond particles that exhibit
an average particle size of about 20 .mu.m or less, and a substrate
including a metal-solvent catalyst therein in a pressure
transmitting medium to form a cell assembly; and subjecting the
cell assembly to a temperature of at least about 1000.degree.
Celsius and a pressure in the pressure transmitting medium of at
least about 7.5 GPa to infiltrate the plurality of diamond
particles with a portion of the metal-solvent catalyst and catalyze
formation of a polycrystalline diamond table bonded to the
substrate, wherein the polycrystalline diamond table includes about
1 weight % to about 7.5 weight % of the metal-solvent catalyst
therein.
19. The method of claim 18 wherein the polycrystalline diamond
table exhibits a coercivity of about 130 Oe to about 160 Oe, a
specific magnetic saturation of about 10 Gcm.sup.3/g to about 15
Gcm.sup.3/g, and the metal-solvent catalyst is present in an amount
of about 3 weight % to about 7.5 weight %.
20. The method of claim 18 wherein the pressure in the pressure
transmitting medium is about 7.5 GPa to about 15 GPa.
21. The method of claim 18 wherein the polycrystalline diamond
table exhibits a coercivity of about 115 Oe or more.
22. The method of claim 18 wherein the polycrystalline diamond
table exhibits a coercivity of about 115 Oe to about 250 Oe and a
specific magnetic saturation of about 5 Gcm.sup.3/g to about 15
Gcm.sup.3/g.
23. The method of claim 18 wherein the polycrystalline diamond
table exhibits a coercivity of about 130 Oe to about 160 Oe, a
specific magnetic saturation of about 10 Gcm.sup.3/g to about 15
Gcm.sup.3/g, and the metal-solvent catalyst is present in an amount
of about 3 weight % to about 6 weight %.
24. The method of claim 18 wherein the amount of the metal-solvent
catalyst present in the polycrystalline diamond table is about 3
weight % to about 6 weight %.
25. The method of claim 18 wherein the amount of the metal-solvent
catalyst present in the polycrystalline diamond table is about 1
weight % to about 3 weight %.
26. The method of claim 18 wherein the polycrystalline diamond
table exhibits a thermal stability of at least about 1300 m as
determined by a distance cut, prior to failure, in a vertical lathe
test.
27. The method of claim 1 wherein the pressure in the pressure
transmitting medium is about 7.5 GPa to about 15 GPa.
Description
BACKGROUND
Wear-resistant, superabrasive compacts are utilized in a variety of
mechanical applications. For example, polycrystalline diamond
compacts ("PDCs") are used in drilling tools (e.g., cutting
elements, gage trimmers, etc.), machining equipment, bearing
apparatuses, wire-drawing machinery, and in other mechanical
apparatuses.
PDCs have found particular utility as superabrasive cutting
elements in rotary drill bits, such as roller-cone drill bits and
fixed-cutter drill bits. A PDC cutting element typically includes a
superabrasive diamond layer commonly referred to as a diamond
table. The diamond table may be formed and bonded to a substrate
using a high-pressure, high-temperature ("HPHT") process. The PDC
cutting element may also be brazed directly into a preformed
pocket, socket, or other receptacle formed in the bit body. The
substrate may often be brazed or otherwise joined to an attachment
member, such as a cylindrical backing. A rotary drill bit typically
includes a number of PDC cutting elements affixed to the bit body.
It is also known that a stud carrying the PDC may be used as a PDC
cutting element when mounted to a bit body of a rotary drill bit by
press-fitting, brazing, or otherwise securing the stud into a
receptacle formed in the bit body.
Conventional PDCs are normally fabricated by placing a cemented
carbide substrate into a container with a volume of diamond
particles positioned adjacent to the cemented carbide substrate. A
number of such cartridges may be loaded into an HPHT press. The
substrates and volume of diamond particles are then processed under
HPHT conditions in the presence of a catalyst material that causes
the diamond particles to bond to one another to form a matrix of
bonded diamond grains defining a polycrystalline diamond ("PCD")
table that is bonded to the substrate. The catalyst material is
often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or
alloys thereof) that is used for promoting intergrowth of the
diamond particles.
In one conventional approach, a constituent of the cemented carbide
substrate, such as cobalt from a cobalt-cemented tungsten carbide
substrate, liquefies and sweeps from a region adjacent to the
volume of diamond particles into interstitial regions between the
diamond particles during the HPHT process. The cobalt acts as a
catalyst to promote intergrowth between the diamond particles,
which results in formation of bonded diamond grains. Often, a
solvent catalyst may be mixed with the diamond particles prior to
subjecting the diamond particles and substrate to the HPHT
process.
The presence of the solvent catalyst in the PCD table is believed
to reduce the thermal stability of the PCD table at elevated
temperatures. For example, the difference in thermal expansion
coefficient between the diamond grains and the solvent catalyst is
believed to lead to chipping or cracking of the PCD table during
drilling or cutting operations, which can degrade the mechanical
properties of the PCD table or cause failure. Additionally, some of
the diamond grains can undergo a chemical breakdown or
back-conversion to graphite via interaction with the solvent
catalyst. At elevated high temperatures, portions of the diamond
grains may transform to carbon monoxide, carbon dioxide, graphite,
or combinations thereof, thus degrading the mechanical properties
of the PDC.
One conventional approach for improving the thermal stability of a
PDC is to at least partially remove the solvent catalyst from the
PCD table of the PDC by acid leaching. However, removing the
solvent catalyst from the PCD table can be relatively time
consuming for high-volume manufacturing. Additionally, depleting
the solvent catalyst may decrease the mechanical strength of the
PCD table.
Despite the availability of a number of different PCD materials,
manufacturers and users of PCD materials continue to seek PCD
materials that exhibit improved mechanical and/or thermal
properties.
SUMMARY
Embodiments of the invention relate to PCD exhibiting enhanced
diamond-to-diamond bonding. In an embodiment, PCD includes a
plurality of diamond grains defining a plurality of interstitial
regions. A metal-solvent catalyst occupies the plurality of
interstitial regions. The plurality of diamond grains and the
metal-solvent catalyst collectively may exhibit a coercivity of
about 115 Oersteds ("Oe") or more and a specific magnetic
saturation of about 15 Gausscm.sup.3/grams ("Gcm.sup.3/g") or
less.
In an embodiment, PCD includes a plurality of diamond grains
defining a plurality of interstitial regions. A metal-solvent
catalyst occupies the plurality of interstitial regions. The
plurality of diamond grains and the metal-solvent catalyst
collectively may exhibit a specific magnetic saturation of about 15
Gcm.sup.3/g or less. The plurality of diamond grains and the
metal-solvent catalyst define a volume of at least about 0.050
cm.sup.3.
In an embodiment, a PDC includes a PCD table bonded to a substrate.
At least a portion of the PCD table may comprise any of the PCD
embodiments disclosed herein.
In an embodiment, a method includes enclosing a plurality of
diamond particles that exhibit an average particle size of about 30
.mu.m or less and a metal-solvent catalyst in a pressure
transmitting medium to form a cell assembly. The method further
includes subjecting the cell assembly to a temperature of at least
about 1000.degree. C. and a pressure in the pressure transmitting
medium of at least about 7.5 GPa to form PCD.
Further embodiments relate to applications utilizing the disclosed
PCD and PDCs in various articles and apparatuses, such as rotary
drill bits, bearing apparatuses, wire-drawing dies, machining
equipment, and other articles and apparatuses.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrate several embodiments of the invention,
wherein identical reference numerals refer to identical elements or
features in different views or embodiments shown in the
drawings.
FIG. 1A is a schematic diagram of an example of a magnetic
saturation apparatus configured to magnetize a PCD sample
approximately to saturation.
FIG. 1B is a schematic diagram of an example of a magnetic
saturation measurement apparatus configured to measure a saturation
magnetization of a PCD sample.
FIG. 2 is a schematic diagram of an example of a coercivity
measurement apparatus configured to determine a coercivity of a PCD
sample.
FIG. 3A is a cross-sectional view of an embodiment of a PDC
including a PCD table formed from any of the PCD embodiments
disclosed herein.
FIG. 3B is a graph illustrating residual principal stress versus
substrate thickness that was measured in a PCD table of a PDC
fabricated at a pressure above about 7.5 GPa and a PCD table of a
conventionally formed PDC.
FIG. 4 is a schematic illustration of a method of fabricating the
PDC shown in FIG. 3A.
FIG. 5A is an isometric view of an embodiment of a rotary drill bit
that may employ one or more of the disclosed PDC embodiments.
FIG. 5B is a top elevation view of the rotary drill bit shown in
FIG. 5A.
FIG. 6 is an isometric cut-away view of an embodiment of a
thrust-bearing apparatus that may utilize one or more of the
disclosed PDC embodiments.
FIG. 7 is an isometric cut-away view of an embodiment of a radial
bearing apparatus that may utilize one or more of the disclosed PDC
embodiments.
FIG. 8 is a schematic isometric cut-away view of an embodiment of a
subterranean drilling system including the thrust-bearing apparatus
shown in FIG. 6.
FIG. 9 is a side cross-sectional view of an embodiment of a
wire-drawing die that employs a PDC fabricated in accordance with
the principles described herein.
DETAILED DESCRIPTION
Embodiments of the invention relate to PCD that exhibits enhanced
diamond-to-diamond bonding. It is currently believed by the
inventors that as the sintering pressure employed during the HPHT
process used to fabricate such PCD is moved further into the
diamond-stable region away from the graphite-diamond equilibrium
line, the rate of nucleation and growth of diamond increases. Such
increased nucleation and growth of diamond between diamond
particles (for a given diamond particle formulation) may result in
PCD being formed exhibiting a relatively lower metal-solvent
catalyst content, a higher coercivity, a lower specific magnetic
saturation, and/or a lower specific permeability (i.e., the ratio
of specific magnetic saturation to coercivity) than PCD formed at a
lower sintering pressure. Embodiments also relate to PDCs having a
PCD table comprising such PCD, methods of fabricating such PCD and
PDCs, and applications for such PCD and PDCs in rotary drill bits,
bearing apparatuses, wire-drawing dies, machining equipment, and
other articles and apparatuses.
PCD Embodiments
According to various embodiments, PCD sintered at a pressure of at
least about 7.5 GPa may exhibit a coercivity of 115 Oe or more, a
high-degree of diamond-to-diamond bonding, a specific magnetic
saturation of about 15 Gcm.sup.3/g or less, and a metal-solvent
catalyst content of about 7.5 weight % ("wt %") or less. The PCD
includes a plurality of diamond grains directly bonded together via
diamond-to-diamond bonding to define a plurality of interstitial
regions. At least a portion of the interstitial regions or, in some
embodiments, substantially all of the interstitial regions may be
occupied by a metal-solvent catalyst, such as iron, nickel, cobalt,
or alloys of any of the foregoing metals. For example, the
metal-solvent catalyst may be a cobalt-based material including at
least 50 wt % cobalt, such as a cobalt alloy.
The diamond grains may exhibit an average grain size of about 50
.mu.m or less, such as about 30 .mu.m or less or about 20 .mu.m or
less. For example, the average grain size of the diamond grains may
be about 10 .mu.m to about 18 .mu.m and, in some embodiments, about
15 .mu.m to about 18 .mu.m. In some embodiments, the average grain
size of the diamond grains may be about 10 .mu.m or less, such as
about 2 .mu.m to about 5 .mu.m or submicron. The diamond grain size
distribution of the diamond grains may exhibit a single mode, or
may be a bimodal or greater grain size distribution.
The metal-solvent catalyst that occupies the interstitial regions
may be present in the PCD in an amount of about 7.5 wt % or less.
In some embodiments, the metal-solvent catalyst may be present in
the PCD in an amount of about 3 wt % to about 7.5 wt %, such as
about 3 wt % to about 6 wt %. In other embodiments, the
metal-solvent catalyst content may be present in the PCD in an
amount less than about 3 wt %, such as about 1 wt % to about 3 wt %
or a residual amount to about 1 wt %. By maintaining the
metal-solvent catalyst content below about 7.5 wt %, the PCD may
exhibit a desirable level of thermal stability suitable for
subterranean drilling applications.
Many physical characteristics of the PCD may be determined by
measuring certain magnetic properties of the PCD because the
metal-solvent catalyst may be ferromagnetic. The amount of the
metal-solvent catalyst present in the PCD may be correlated with
the measured specific magnetic saturation of the PCD. A relatively
larger specific magnetic saturation indicates relatively more
metal-solvent catalyst in the PCD.
The mean free path between neighboring diamond grains of the PCD
may be correlated with the measured coercivity of the PCD. A
relatively large coercivity indicates a relatively smaller mean
free path. The mean free path is representative of the average
distance between neighboring diamond grains of the PCD, and thus
may be indicative of the extent of diamond-to-diamond bonding in
the PCD. A relatively smaller mean free path, in well-sintered PCD,
may indicate relatively more diamond-to-diamond bonding.
As merely one example, ASTM B886-03 (2008) provides a suitable
standard for measuring the specific magnetic saturation and ASTM
B887-03 (2008) e1 provides a suitable standard for measuring the
coercivity of the PCD. Although both ASTM B886-03 (2008) and ASTM
B887-03 (2008) e1 are directed to standards for measuring magnetic
properties of cemented carbide materials, either standard may be
used to determine the magnetic properties of PCD. A KOERZIMAT CS
1.096 instrument (commercially available from Foerster Instruments
of Pittsburgh, Pa.) is one suitable instrument that may be used to
measure the specific magnetic saturation and the coercivity of the
PCD.
Generally, as the sintering pressure that is used to form the PCD
increases, the coercivity may increase and the magnetic saturation
may decrease. The PCD defined collectively by the bonded diamond
grains and the metal-solvent catalyst may exhibit a coercivity of
about 115 Oe or more and a metal-solvent catalyst content of less
than about 7.5 wt % as indicated by a specific magnetic saturation
of about 15 Gcm.sup.3/g or less. In a more detailed embodiment, the
coercivity of the PCD may be about 115 Oe to about 250 Oe and the
specific magnetic saturation of the PCD may be greater than 0
Gcm.sup.3/g to about 15 Gcm.sup.3/g. In an even more detailed
embodiment, the coercivity of the PCD may be about 115 Oe to about
175 Oe and the specific magnetic saturation of the PCD may be about
5 Gcm.sup.3/g to about 15 Gcm.sup.3/g. In yet an even more detailed
embodiment, the coercivity of the PCD may be about 155 Oe to about
175 Oe and the specific magnetic saturation of the PCD may be about
10 Gcm.sup.3/g to about 15 Gcm.sup.3/g. The specific permeability
(i.e., the ratio of specific magnetic saturation to coercivity) of
the PCD may be about 0.10 or less, such as about 0.060 to about
0.090. Despite the average grain size of the bonded diamond grains
being less than about 30 .mu.m, the metal-solvent catalyst content
in the PCD may be less than about 7.5 wt % resulting in a desirable
thermal stability.
In one embodiment, diamond particles having an average particle
size of about 18 .mu.m to about 20 .mu.m are positioned adjacent to
a cobalt-cemented tungsten carbide substrate and subjected to an
HPHT process at a temperature of about 1390.degree. C. to about
1430.degree. C. and a pressure of about 7.8 GPa to about 8.5 GPa.
The PCD so-formed as a PCD table bonded to the substrate may
exhibit a coercivity of about 155 Oe to about 175 Oe, a specific
magnetic saturation of about 10 Gcm.sup.3/g to about 15
Gcm.sup.3/g, and a cobalt content of about 5 wt % to about 7.5 wt
%.
In one or more embodiments, a specific magnetic saturation constant
for the metal-solvent catalyst in the PCD may be about 185
Gcm.sup.3/g to about 215 Gcm.sup.3/g. For example, the specific
magnetic saturation constant for the metal-solvent catalyst in the
PCD may be about 195 Gcm.sup.3/g to about 205 Gcm.sup.3/g. It is
noted that the specific magnetic saturation constant for the
metal-solvent catalyst in the PCD may be composition dependent.
Generally, as the sintering pressure is increased above 7.5 GPa, a
wear resistance of the PCD so-formed may increase. For example, the
G.sub.ratio may be at least about 4.0.times.10.sup.6, such as about
5.0.times.10.sup.6 to about 15.0.times.10.sup.6 or, more
particularly, about 8.0.times.10.sup.6 to about
15.0.times.10.sup.6. In some embodiments, the G.sub.ratio may be at
least about 30.0.times.10.sup.6. The G.sub.ratio is the ratio of
the volume of workpiece cut to the volume of PCD worn away during
the cutting process. An example of suitable parameters that may be
used to determine a G.sub.ratio of the PCD are a depth of cut for
the PCD cutting element of about 0.254 mm, a back rake angle for
the PCD cutting element of about 20 degrees, an in-feed for the PCD
cutting element of about 6.35 mm/rev, a rotary speed of the
workpiece to be cut of about 101 rpm, and the workpiece may be made
from Barre granite having a 914 mm outer diameter and a 254 mm
inner diameter. During the G.sub.ratio test, the workpiece is
cooled with a coolant, such as water.
In addition to the aforementioned G.sub.ratio, despite the presence
of the metal-solvent catalyst in the PCD, the PCD may exhibit a
thermal stability that is close to, substantially the same as, or
greater than a partially leached PCD material formed by sintering a
substantially similar diamond particle formulation at a lower
sintering pressure (e.g., up to about 5.5 GPa) and in which the
metal-solvent catalyst (e.g., cobalt) is leached therefrom to a
depth of about 60 .mu.m to about 100 .mu.m from a working surface.
The thermal stability of the PCD may be evaluated by measuring the
distance cut in a workpiece prior to catastrophic failure, without
using coolant, in a vertical lathe test (e.g., vertical turret
lathe or a vertical boring mill). An example of suitable parameters
that may be used to determine thermal stability of the PCD are a
depth of cut for the PCD cutting element of about 1.27 mm, a back
rake angle for the PCD cutting element of about 20 degrees, an
in-feed for the PCD cutting element of about 1.524 mm/rev, a
cutting speed of the workpiece to be cut of about 1.78 m/sec, and
the workpiece may be made from Barre granite having a 914 mm outer
diameter and a 254 mm inner diameter. In an embodiment, the
distance cut in a workpiece prior to catastrophic failure as
measured in the above-described vertical lathe test may be at least
about 1300 m, such as about 1300 m to about 3950 m.
PCD formed by sintering diamond particles having the same diamond
particle size distribution as a PCD embodiment of the invention,
but sintered at a pressure of, for example, up to about 5.5 GPa and
at temperatures in which diamond is stable may exhibit a coercivity
of about 100 Oe or less and/or a specific magnetic saturation of
about 16 Gcm.sup.3/g or more. Thus, in one or more embodiments of
the invention, PCD exhibits a metal-solvent catalyst content of
less than 7.5 wt % and a greater amount of diamond-to-diamond
bonding between diamond grains than that of a PCD sintered at a
lower pressure, but with the same precursor diamond particle size
distribution and catalyst.
It is currently believed by the inventors that forming the PCD by
sintering diamond particles at a pressure of at least about 7.5 GPa
may promote nucleation and growth of diamond between the diamond
particles being sintered so that the volume of the interstitial
regions of the PCD so-formed is decreased compared to the volume of
interstitial regions if the same diamond particle distribution was
sintered at a pressure of, for example, up to about 5.5 GPa and at
temperatures where diamond is stable. For example, the diamond may
nucleate and grow from carbon provided by dissolved carbon in
metal-solvent catalyst (e.g., liquefied cobalt) infiltrating into
the diamond particles being sintered, partially graphitized diamond
particles, carbon from a substrate, carbon from another source
(e.g., graphite particles and/or fullerenes mixed with the diamond
particles), or combinations of the foregoing. This nucleation and
growth of diamond in combination with the sintering pressure of at
least about 7.5 GPa may contribute to PCD so-formed having a
metal-solvent catalyst content of less than about 7.5 wt %.
FIGS. 1A, 1B, and 2 schematically illustrate the mariner in which
the specific magnetic saturation and the coercivity of the PCD may
be determined using an apparatus, such as the KOERZIMAT CS 1.096
instrument. FIG. 1A is a schematic diagram of an example of a
magnetic saturation apparatus 100 configured to magnetize a PCD
sample to saturation. The magnetic saturation apparatus 100
includes a saturation magnet 102 of sufficient strength to
magnetize a PCD sample 104 to saturation. The saturation magnet 102
may be a permanent magnet or an electromagnet. In the illustrated
embodiment, the saturation magnet 102 is a permanent magnet that
defines an air gap 106, and the PCD sample 104 may be positioned on
a sample holder 108 within the air gap 106. When the PCD sample 104
is light-weight, it may be secured to the sample holder 108 using,
for example, double-sided tape or other adhesive so that the PCD
sample 104 does not move responsive to the magnetic field from the
saturation magnet 102 and the PCD sample 104 is magnetized
approximately to saturation.
Referring to the schematic diagram of FIG. 1B, after magnetizing
the PCD sample 104 approximately to saturation using the magnetic
saturation apparatus 100, a magnetic saturation of the PCD sample
104 may be measured using a magnetic saturation measurement
apparatus 120. The magnetic saturation measurement apparatus 120
includes a Helmholtz measuring coil 122 defining a passageway
dimensioned so that the magnetized PCD sample 104 may be positioned
therein on a sample holder 124. Once positioned in the passageway,
the sample holder 124 supporting the magnetized PCD sample 104 may
be moved axially along an axis direction 126 to induce a current in
the Helmholtz measuring coil 122. Measurement electronics 128 are
coupled to the Helmholtz measuring coil 122 and configured to
calculate the magnetic saturation based upon the measured current
passing through the Helmholtz measuring coil 122. The measurement
electronics 128 may also be configured to calculate a weight
percentage of magnetic material in the PCD sample 104 when the
composition and magnetic characteristics of the metal-solvent
catalyst in the PCD sample 104 are known, such as with iron,
nickel, cobalt, and alloys thereof. Specific magnetic saturation
may be calculated based upon the calculated magnetic saturation and
the measured weight of the PCD sample 104.
The amount of metal-solvent catalyst in the PCD sample 104 may be
determined using a number of different analytical techniques. For
example, energy dispersive spectroscopy (e.g., EDAX), wavelength
dispersive x-ray spectroscopy (e.g., WDX), and/or Rutherford
backscattering spectroscopy may be employed to determine the amount
of metal-solvent catalyst in the PCD sample 104.
If desired, a specific magnetic saturation constant of the
metal-solvent catalyst content in the PCD sample 104 may be
determined using an iterative approach. A value for the specific
magnetic saturation constant of the metal-solvent catalyst in the
PCD sample 104 may be iteratively chosen until a metal-solvent
catalyst content calculated by the analysis software of the
KOERZIMAT CS 1.096 instrument using the chosen value substantially
matches the metal-solvent catalyst content determined via an
analytical technique, such as energy dispersive spectroscopy,
wavelength dispersive x-ray spectroscopy, and/or Rutherford
backscattering spectroscopy.
FIG. 2 is a schematic diagram of a coercivity measurement apparatus
200 configured to determine a coercivity of a PCD sample. The
coercivity measurement apparatus 200 includes a coil 202 and
measurement electronics 204 coupled to the coil 202. The
measurement electronics 204 are configured to pass a current
through the coil 202 so that a magnetic field is generated. A
sample holder 206 having a PCD sample 208 thereon may be positioned
within the coil 202. A magnetization sensor 210 configured to
measure a magnetization of the PCD sample 208 may be coupled to the
measurement electronics 204 and positioned in proximity to the PCD
sample 208.
During testing, the magnetic field generated by the coil 202
magnetizes the PCD sample 208 approximately to saturation. Then,
the measurement electronics 204 apply a current so that the
magnetic field generated by the coil 202 is increasingly reversed.
The magnetization sensor 210 measures a magnetization of the PCD
sample 208 resulting from application of the reversed magnetic
field to the PCD sample 208. The measurement electronics 204
determine the coercivity of the PCD sample 208, which is a
measurement of the reverse magnetic field at which the
magnetization of the PCD sample 208 is zero.
Embodiments of Methods for Fabricating PCD
The PCD may be formed by sintering a mass of a plurality of diamond
particles in the presence of a metal-solvent catalyst. The diamond
particles may exhibit an average particle size of about 50 .mu.m or
less, such as about 30 .mu.m or less, about 20 .mu.m or less, about
10 .mu.m to about 18 .mu.m, or about 15 .mu.m to about 18 .mu.m. In
some embodiments, the average particle size of the diamond
particles may be about 10 .mu.m or less, such as about 2 .mu.m to
about 5 .mu.m or submicron.
In an embodiment, the diamond particles of the mass of diamond
particles may comprise a relatively larger size and at least one
relatively smaller size. As used herein, the phrases "relatively
larger" and "relatively smaller" refer to particle sizes (by any
suitable method) that differ by at least a factor of two (e.g., 30
.mu.m and 15 .mu.m). According to various embodiments, the mass of
diamond particles may include a portion exhibiting a relatively
larger size (e.g., 30 .mu.m, 20 .mu.m, 15 .mu.m, 12 .mu.m, 10
.mu.m, 8 .mu.m) and another portion exhibiting at least one
relatively smaller size (e.g., 6 .mu.m, 5 .mu.m, 4 .mu.m, 3 .mu.m,
2 .mu.m, 1 .mu.m, 0.5 .mu.m, less than 0.5 .mu.m, 0.1 .mu.m, less
than 0.1 .mu.m). In one embodiment, the mass of diamond particles
may include a portion exhibiting a relatively larger size between
about 10 .mu.m and about 40 .mu.m and another portion exhibiting a
relatively smaller size between about 1 .mu.m and 4 .mu.m. In some
embodiments, the mass of diamond particles may comprise three or
more different sizes (e.g., one relatively larger size and two or
more relatively smaller sizes), without limitation.
It is noted that the as-sintered diamond grain size may differ from
the average particle size of the mass of diamond particles prior to
sintering due to a variety of different physical processes, such as
grain growth, diamond particles fracturing, carbon provided from
another carbon source (e.g., dissolved carbon in the metal-solvent
catalyst), or combinations of the foregoing. The metal-solvent
catalyst (e.g., iron, nickel, cobalt, or alloys thereof) may be
provided in particulate form mixed with the diamond particles, as a
thin foil or plate placed adjacent to the mass of diamond
particles, from a cemented carbide substrate including a
metal-solvent catalyst, or combinations of the foregoing.
In order to efficiently sinter the mass of diamond particles, the
mass may be enclosed in a pressure transmitting medium, such as a
refractory metal can, graphite structure, pyrophyllite, and/or
other suitable pressure transmitting structure to form a cell
assembly. Examples of suitable gasket materials and cell structures
for use in manufacturing PCD are disclosed in U.S. Pat. No.
6,338,754 and U.S. patent application Ser. No. 11/545,929, each of
which is incorporated herein, in its entirety, by this reference.
Another example of a suitable pressure transmitting material is
pyrophyllite, which is commercially available from Wonderstone Ltd.
of South Africa. The cell assembly, including the pressure
transmitting medium and mass of diamond particles therein, is
subjected to an HPHT process using an ultra-high pressure press at
a temperature of at least about 1000.degree. C. (e.g., about
1100.degree. C. to about 2200.degree. C., or about 1200.degree. C.
to about 1450.degree. C.) and a pressure in the pressure
transmitting medium of at least about 7.5 GPa (e.g., about 7.5 GPa
to about 15 GPa) for a time sufficient to sinter the diamond
particles together in the presence of the metal-solvent catalyst
and form the PCD comprising bonded diamond grains defining
interstitial regions occupied by the metal-solvent catalyst. For
example, the pressure in the pressure transmitting medium employed
in the HPHT process may be at least about 8.0 GPa, at least about
9.0 GPa, at least about 10.0 GPa, at least about 11.0 GPa, at least
about 12.0 GPa, or at least about 14 GPa.
The pressure values employed in the HPHT processes disclosed herein
refer to the pressure in the pressure transmitting medium at room
temperature (e.g., about 25.degree. C.) with application of
pressure using an ultra-high pressure press and not the pressure
applied to exterior of the cell assembly. The actual pressure in
the pressure transmitting medium at sintering temperature may be
slightly higher. The ultra-high pressure press may be calibrated at
room temperature by embedding at least one calibration material
that changes structure at a known pressure, such as PbTe, thallium,
barium, or bismuth in the pressure transmitting medium. Further,
optionally, a change in resistance may be measured across the at
least one calibration material due to a phase change thereof. For
example, PbTe exhibits a phase change at room temperature at about
6.0 GPa and bismuth exhibits a phase change at room temperature at
about 7.7 GPa. Examples of suitable pressure calibration techniques
are disclosed in G. Rousse, S. Klotz, A. M. Saitta, J.
Rodriguez-Carvajal, M. I. McMahon, B. Couzinet, and M. Mezouar,
"Structure of the Intermediate Phase of PbTe at High Pressure,"
Physical Review B: Condensed Matter and Materials Physics, 71,
224116 (2005) and D. L. Decker, W. A. Bassett, L. Merrill, H. T.
Hall, and J. D. Barnett, "High-Pressure Calibration: A Critical
Review," J. Phys. Chem. Ref. Data, 1, 3 (1972).
In an embodiment, a pressure of at least about 7.5 GPa in the
pressure transmitting medium may be generated by applying pressure
to a cubic high-pressure cell assembly that encloses the mass of
diamond particles to be sintered using anvils, with each anvil
applying pressure to a different face of the cubic high-pressure
assembly. In such an embodiment, a surface area of each anvil face
of the anvils may be selectively dimensioned to facilitate
application of pressure of at least about 7.5 GPa to the mass of
diamond particles being sintered. For example, the surface area of
each anvil may be less than about 12.0 cm.sup.2, such as about 8
cm.sup.2 to about 10 cm.sup.2. The anvils may be made from a
cobalt-cemented tungsten carbide or other material having a
sufficient compressive strength to help reduce damage thereto
through repetitive use in a high-volume commercial manufacturing
environment. Optionally, as an alternative to or in addition to
selectively dimensioning the surface area of each anvil face, two
or more internal anvils may be embedded in the cubic high-pressure
cell assembly to further intensify pressure. For example, the
article W. Utsumi, N. Toyama, S. Endo and F. E. Fujita, "X-ray
diffraction under ultrahigh pressure generated with sintered
diamond anvils," J. Appl. Phys., 60, 2201 (1986) is incorporated
herein, in its entirety, by this reference and discloses that
sintered diamond anvils may be embedded in a cubic pressure
transmitting medium for intensifying the pressure applied by an
ultra-high pressure press to a workpiece also embedded in the cubic
pressure transmitting medium.
PDC Embodiments and Methods of Fabricating PDCs
Referring to FIG. 3A, the PCD embodiments may be employed in a PDC
for cutting applications, bearing applications, or many other
applications. FIG. 3A is a cross-sectional view of an embodiment of
a PDC 300. The PDC 300 includes a substrate 302 bonded to a PCD
table 304. The PCD table 304 may be formed of PCD in accordance
with any of the PCD embodiments disclosed herein. The PCD table 304
exhibits at least one working surface 306 and at least one lateral
dimension "d" (e.g., a diameter). Although FIG. 1 shows the working
surface 306 as substantially planar, the working surface 306 may be
concave, convex, or another nonplanar geometry. The substrate 302
may be generally cylindrical or another selected configuration,
without limitation. Although FIG. 1 shows an interfacial surface
308 of the substrate 302 as being substantially planar, the
interfacial surface 308 may exhibit a selected nonplanar
topography, such as a grooved, ridged, or other nonplanar
interfacial surface. The substrate 302 may include, without
limitation, cemented carbides, such as tungsten carbide, titanium
carbide, chromium carbide, niobium carbide, tantalum carbide,
vanadium carbide, or combinations thereof cemented with iron,
nickel, cobalt, or alloys thereof. For example, in one embodiment,
the substrate 302 comprises cobalt-cemented tungsten carbide.
FIG. 4 is a schematic illustration of an embodiment of a method for
fabricating the PDC 300 shown in FIG. 3A. Referring to FIG. 4, a
mass of diamond particles 400 having any of the above-mentioned
average particle sizes and distributions (e.g., an average particle
size of about 50 .mu.m or less) is positioned adjacent to the
interfacial surface 308 of the substrate 302. As previously
discussed, the substrate 302 may include a metal-solvent catalyst.
The mass of diamond particles 400 and substrate 302 may be
subjected to an HPHT process using conditions previously described
with respect to sintering the PCD embodiments disclosed herein. The
PDC 300 so-formed includes the PCD table 304 that comprises PCD,
formed of any of the PCD embodiments disclosed herein, integrally
formed with the substrate 302 and bonded to the interfacial surface
308 of the substrate 302. If the substrate 302 includes a
metal-solvent catalyst, the metal-solvent catalyst may liquefy and
infiltrate the mass of diamond particles 400 to promote growth
between adjacent diamond particles of the mass of diamond particles
400 to form the PCD table 304 comprised of a body of bonded diamond
grains having the infiltrated metal-solvent catalyst interstitially
disposed between bonded diamond grains. For example, if the
substrate 302 is a cobalt-cemented tungsten carbide substrate,
cobalt from the substrate 302 may be liquefied and infiltrate the
mass of diamond particles 400 to catalyze formation of the PCD
table 304.
Employing selectively dimensioned anvil faces and/or internal
anvils in the ultra-high pressure press used to process the mass of
diamond particles 400 and substrate 302 enables forming the at
least one lateral dimension "d" of the PCD table 304 to be about
0.80 cm or more. Referring again to FIG. 3A, for example, the at
least one lateral dimension "d" may be about 0.80 cm to about 3.0
cm and, in some embodiments, about 1.3 cm to about 1.9 cm or about
1.6 cm to about 1.9 cm. A representative volume of the PCD table
304 (or any PCD article of manufacture disclosed herein) formed
using the selectively dimensioned anvil faces and/or internal
anvils may be at least about 0.050 cm.sup.3. For example, the
volume may be about 0.25 cm.sup.3 to at least about 1.25 cm.sup.3
or about 0.1 cm.sup.3 to at least about 0.70 cm.sup.3. A
representative volume for the PDC 300 may be about 0.4 cm.sup.3 to
at least about 4.6 cm.sup.3, such as about 1.1 cm.sup.3 to at least
about 2.3 cm.sup.3.
In other embodiments, a PCD table according to an embodiment may be
separately formed using an HPHT sintering process and,
subsequently, bonded to the interfacial surface 308 of the
substrate 302 by brazing, using a separate HPHT bonding process, or
any other suitable joining technique, without limitation. In yet
another embodiment, a substrate may be formed by depositing a
binderless carbide (e.g., tungsten carbide) via chemical vapor
deposition onto the separately formed PCD table.
In any of the embodiments disclosed herein, substantially all or a
selected portion of the metal-solvent catalyst may be removed
(e.g., via leaching) from the PCD table. In an embodiment,
metal-solvent catalyst in the PCD table may be removed to a
selected depth from at least one exterior working surface (e.g.,
the working surface 306 and/or a sidewall working surface of the
PCD table 304) so that only a portion of the interstitial regions
are occupied by metal-solvent catalyst. For example, substantially
all or a selected portion of the metal-solvent catalyst may be
removed from the PCD table 304 so-formed in the PDC 300 to a
selected depth from the working surface 306.
In another embodiment, a PCD table may be fabricated according to
any of the disclosed embodiments in a first HPHT process, leached
to remove substantially all of the metal-solvent catalyst from the
interstitial regions between the bonded diamond grains, and
subsequently bonded to a substrate in a second HPHT process. In the
second HPHT process, an infiltrant from, for example, a cemented
carbide substrate may infiltrate into the interstitial regions from
which the metal-solvent catalyst was depleted. For example, the
infiltrant may be cobalt that is swept-in from a cobalt-cemented
tungsten carbide substrate. In one embodiment, the first and/or
second HPHT process may be performed at a pressure of at least
about 7.5 GPa. In one embodiment, the infiltrant may be leached
from the infiltrated PCD table using a second acid leaching process
following the second HPHT process.
In some embodiments, the pressure employed in the HPHT process used
to fabricate the PDC 300 may be sufficient to reduce residual
stresses in the PCD table 304 that develop during the HPHT process
due to the thermal expansion mismatch between the substrate 302 and
the PCD table 304. In such an embodiment, the principal stress
measured on the working surface 306 of the PDC 300 may exhibit a
value of about -345 MPa to about 0 MPa, such as about -289 MPa. For
example, the principal stress measured on the working surface 306
may exhibit a value of about -345 MPa to about 0 MPa. A
conventional PDC fabricated using an HPHT process at a pressure
below about 7.5 GPa may result in a PCD table thereof exhibiting a
principal stress on a working surface thereof of about -1724 MPa to
about -414 MPa, such as about -770 MPa.
Residual stress may be measured on the working surface 306 of the
PCD table 304 of the PDC 300 as described in T. P. Lin, M. Hood, G.
A. Cooper, and R. H. Smith, "Residual stresses in polycrystalline
diamond compacts," J. Am. Ceram. Soc. 77, 6, 1562-1568 (1994). More
particularly, residual strain may be measured with a rosette strain
gage bonded to the working surface 306. Such strain may be measured
for different levels of removal of the substrate 302 (e.g., as
material is removed from the back of the substrate 302). Residual
stress may be calculated from the measured residual strain
data.
FIG. 3B is a graph of residual principal stress versus substrate
thickness that was measured in a PCD table of a PDC fabricated at
pressure above about 7.5 GPa in accordance with an embodiment of
the invention and a PCD table of a conventionally formed PDC. The
residual principal stress was determined using the technique
described in the article referenced above by Lin et al. Curve 310
shows the measured residual principal stress on a working surface
of the PDC fabricated at a pressure above about 7.5 GPa. The PDC
that was fabricated at a pressure above about 7.5 GPa had a
thickness dimension of about 1 mm and the substrate had a thickness
dimension of about 7 mm and a diameter of about 13 mm. Curve 312
shows the measured residual principal stress on a working surface
of a PCD table of a conventionally PDC fabricated at pressure below
about 7.5 GPa. The PDC that was fabricated at a pressure below
about 7.5 GPa had a thickness dimension of about 1 mm and the
substrate had a thickness dimension of about 7 mm and a diameter of
about 13 mm. The highest absolute value of the residual principal
stress occurs with the full substrate length of about 7 mm. As
shown by the curves 310 and 312, increasing the pressure, employed
in the HPHT process used to fabricate a PDC, above about 7.5 GPa
may reduce the highest absolute value of the principal residual
stress in a PCD table thereof by about 60% relative to a
conventionally fabricated PDC. For example, at the full substrate
length, the absolute value of the principal residual stress in the
PCD table fabricated at a pressure above about 7.5 GPa is about 60%
less than the absolute value of the principal residual stress in
the PCD table of the conventionally fabricated PDC.
The following working examples provide further detail about the
magnetic properties of PCD tables of PDCs fabricated in accordance
with the principles of some of the specific embodiments of the
invention. The magnetic properties of each PCD table listed in
Tables I-IV were tested using a KOERZIMAT CS 1.096 instrument that
is commercially available from Foerster Instruments of Pittsburgh,
Pa. The specific magnetic saturation of each PCD table was measured
in accordance with ASTM B886-03 (2008) and the coercivity of each
PCD table was measured using ASTM B887-03 (2008)e1 using a
KOERZIMAT CS 1.096 instrument. The amount of cobalt-based
metal-solvent catalyst in the tested PCD tables was determined
using energy dispersive spectroscopy and Rutherford backscattering
spectroscopy. The specific magnetic saturation constant of the
cobalt-based metal-solvent catalyst in the tested PCD tables was
determined to be about 201 Gcm.sup.3/g using an iterative analysis
as previously described. When a value of 201 Gcm.sup.3/g was used
for the specific magnetic saturation constant of the cobalt-based
metal-solvent catalyst, the calculated amount of the cobalt-based
metal-solvent catalyst in the tested PCD tables using the analysis
software of the KOERZIMAT CS 1.096 instrument substantially matched
the measurements using energy dispersive spectroscopy and
Rutherford spectroscopy.
Table I below lists PCD tables that were fabricated in accordance
with the principles of certain embodiments of the invention
discussed above. Each PCD table was fabricated by placing a mass of
diamond particles having the listed average diamond particle size
adjacent to a cobalt-cemented tungsten carbide substrate in a
niobium container, placing the container in a high-pressure cell
medium, and subjecting the high-pressure cell medium and the
container therein to an HPHT process using an HPHT cubic press to
form a PCD table bonded to the substrate. The surface area of each
anvil of the HPHT press and the hydraulic line pressure used to
drive the anvils were selected so that the sintering pressure was
at least about 7.8 GPa. The temperature of the HPHT process was
about 1400.degree. C. and the sintering pressure was at least about
7.8 GPa. The sintering pressures listed in Table I refer to the
pressure in the high-pressure cell medium at room temperature, and
the actual sintering pressures at the sintering temperature are
believed to be greater. After the HPHT process, the PCD table was
removed from the substrate by grinding away the substrate. However,
the substrate may also be removed using electro-discharge machining
or another suitable method.
TABLE-US-00001 TABLE I Selected Magnetic Properties of PCD Tables
Fabricated According to Embodiments of the Invention Specific
Average Sintering Magnetic Specific Diamond Pressure Saturation
Calculated Coercivity Permeability Particle Size (.mu.m) (GPa) (G
cm.sup.3/g) Co wt % (Oe) (G cm.sup.3/g Oe) 1 20 7.8 11.15 5.549
130.2 0.08564 2 19 7.8 11.64 5.792 170.0 0.06847 3 19 7.8 11.85
5.899 157.9 0.07505 4 19 7.8 11.15 5.550 170.9 0.06524 5 19 7.8
11.43 5.689 163.6 0.06987 6 19 7.8 10.67 5.150 146.9 0.07263 7 19
7.8 10.76 5.357 152.3 0.07065 8 19 7.8 10.22 5.087 145.2 0.07039 9
19 7.8 10.12 5.041 156.6 0.06462 10 19 7.8 10.72 5.549 137.1
0.07819 11 11 7.8 12.52 6.229 135.3 0.09254 12 11 7.8 12.78 6.362
130.5 0.09793 13 11 7.8 12.69 6.315 134.6 0.09428 14 11 7.8 13.20
6.569 131.6 0.1003
Table II below lists conventional PCD tables that were fabricated.
Each PCD table listed in Table II was fabricated by placing a mass
of diamond particles having the listed average diamond particle
size adjacent to a cobalt-cemented tungsten carbide substrate in a
niobium container, placing the container in a high-pressure cell
medium, and subjecting the high-pressure cell medium and the
container therein to an HPHT process using an HPHT cubic press to
form a PCD table bonded to the substrate. The surface area of each
anvil of the HPHT press and the hydraulic line pressure used to
drive the anvils were selected so that the sintering pressure was
about 4.6 GPa. Except for samples 15, 16, 18, and 19, which were
subjected to a temperature of about 1430.degree. C., the
temperature of the HPHT process was about 1400.degree. C. and the
sintering pressure was about 4.6 GPa. The sintering pressures
listed in Table II refer to the pressure in the high-pressure cell
medium at room temperature. After the HPHT process, the PCD table
was removed from the cobalt-cemented tungsten carbide substrate by
grinding away the cobalt-cemented tungsten carbide substrate.
TABLE-US-00002 TABLE II Selected Magnetic Properties of Several
Conventional PCD Tables Specific Average Sintering Magnetic
Specific Diamond Pressure Saturation Calculated Coercivity
Permeability Particle Size (.mu.m) (GPa) (G cm.sup.3/g) Co wt %
(Oe) (G cm.sup.3/g Oe) 15 20 4.61 19.30 9.605 94.64 0.2039 16 20
4.61 19.52 9.712 96.75 0.2018 17 20 4.61 19.87 9.889 94.60 0.2100
18 20 5.08 18.61 9.260 94.94 0.1960 19 20 5.08 18.21 9.061 100.4
0.1814 20 20 5.86 16.97 8.452 108.3 0.1567 21 20 4.61 17.17 8.543
102.0 0.1683 22 20 4.61 17.57 8.745 104.9 0.1675 23 20 5.08 16.10
8.014 111.2 0.1448 24 20 5.08 16.79 8.357 107.1 0.1568
As shown in Tables I and II, the conventional PCD tables listed in
Table II exhibit a higher cobalt content therein than the PCD
tables listed in Table I as indicated by the relatively higher
specific magnetic saturation values. Additionally, the conventional
PCD tables listed in Table II exhibit a lower coercivity indicative
of a relatively greater mean free path between diamond grains, and
thus may indicate relatively less diamond-to-diamond bonding
between the diamond grains. Thus, the PCD tables according to
examples of the invention listed in Table I may exhibit
significantly less cobalt therein and a lower mean free path
between diamond grains than the PCD tables listed in Table II.
Table III below lists conventional PCD tables that were obtained
from PDCs. Each PCD table listed in Table III was separated from a
cobalt-cemented tungsten carbide substrate bonded thereto by
grinding.
TABLE-US-00003 TABLE III Selected Magnetic Properties of Several
Conventional PCD Tables Specific Magnetic Specific Saturation
Calculated Coercivity Permeability (G cm.sup.3/g) Co wt % (Oe) (G
cm.sup.3/g Oe) 25 17.23 8.572 140.4 0.1227 26 16.06 7.991 150.2
0.1069 27 15.19 7.560 146.1 0.1040 28 17.30 8.610 143.2 0.1208 29
17.13 8.523 152.1 0.1126 30 17.00 8.458 142.5 0.1193 31 17.08 8.498
147.2 0.1160 32 16.10 8.011 144.1 0.1117
Table IV below lists conventional PCD tables that were obtained
from PDCs. Each PCD table listed in Table IV was separated from a
cobalt-cemented tungsten carbide substrate bonded thereto by
grinding the substrate away. Each PCD table listed in Table IV and
tested had a leached region from which cobalt was depleted and an
unleached region in which cobalt is interstitially disposed between
bonded diamond grains. The leached region was not removed. However,
to determine the specific magnetic saturation and the coercivity of
the unleached region of the PCD table having metal-solvent catalyst
occupying interstitial regions therein, the leached region may be
ground away so that only the unleached region of the PCD table
remains. It is expected that the leached region causes the specific
magnetic saturation to be lower and the coercivity to be higher
than if the leached region was removed and the unleached region was
tested.
TABLE-US-00004 TABLE IV Selected Magnetic Properties of Several
Conventional Leached PCD Tables Specific Magnetic Specific
Saturation Calculated Coercivity Permeability (G cm.sup.3/g) Co wt
% (Oe) (G cm.sup.3/g Oe) 33 17.12 8.471 143.8 0.1191 34 13.62 6.777
137.3 0.09920 35 15.87 7.897 140.1 0.1133 36 12.95 6.443 145.5
0.0890 37 13.89 6.914 142.0 0.09782 38 13.96 6.946 146.9 0.09503 39
13.67 6.863 133.8 0.1022 40 12.80 6.369 146.3 0.08749
As shown in Tables I, III, and IV, the conventional PCD tables of
Tables III and IV exhibit a higher cobalt content therein than the
PCD tables listed in Table I as indicated by the relatively higher
specific magnetic saturation values. This is believed by the
inventors to be a result of the PCD tables listed in Tables III and
IV being formed by sintering diamond particles having a relatively
greater percentage of fine diamond particles than the diamond
particle formulations used to fabricate the PCD tables listed in
Table I.
Embodiments of Applications for PCD and PDCs
The disclosed PCD and PDC embodiments may be used in a number of
different applications including, but not limited to, use in a
rotary drill bit (FIGS. 5A and 5B), a thrust-bearing apparatus
(FIG. 6), a radial bearing apparatus (FIG. 7), a subterranean
drilling system (FIG. 8), and a wire-drawing die (FIG. 9). The
various applications discussed above are merely some examples of
applications in which the PCD and PDC embodiments may be used.
Other applications are contemplated, such as employing the
disclosed PCD and PDC embodiments in friction stir welding
tools.
FIG. 5A is an isometric view and FIG. 5B is a top elevation view of
an embodiment of a rotary drill bit 500. The rotary drill bit 500
includes at least one PDC configured according to any of the
previously described PDC embodiments. The rotary drill bit 500
comprises a bit body 502 that includes radially and longitudinally
extending blades 504 with leading faces 506, and a threaded pin
connection 508 for connecting the bit body 502 to a drilling
string. The bit body 502 defines a leading end structure for
drilling into a subterranean formation by rotation about a
longitudinal axis 510 and application of weight-on-bit. At least
one PDC cutting element, configured according to any of the
previously described PDC embodiments (e.g., the PDC 300 shown in
FIG. 3A), may be affixed to the bit body 502. With reference to
FIG. 5B, a plurality of PDCs 512 are secured to the blades 504. For
example, each PDC 512 may include a PCD table 514 bonded to a
substrate 516. More generally, the PDCs 512 may comprise any PDC
disclosed herein, without limitation. In addition, if desired, in
some embodiments, a number of the PDCs 512 may be conventional in
construction. Also, circumferentially adjacent blades 504 define
so-called junk slots 518 therebetween, as known in the art.
Additionally, the rotary drill bit 500 may include a plurality of
nozzle cavities 520 for communicating drilling fluid from the
interior of the rotary drill bit 500 to the PDCs 512.
FIGS. 5A and 5B merely depict an embodiment of a rotary drill bit
that employs at least one cutting element comprising a PDC
fabricated and structured in accordance with the disclosed
embodiments, without limitation. The rotary drill bit 500 is used
to represent any number of earth-boring tools or drilling tools,
including, for example, core bits, roller-cone bits, fixed-cutter
bits, eccentric bits, bicenter bits, reamers, reamer wings, or any
other downhole tool including PDCs, without limitation.
The PCD and/or PDCs disclosed herein (e.g., the PDC 300 shown in
FIG. 3A) may also be utilized in applications other than rotary
drill bits. For example, the disclosed PDC embodiments may be used
in thrust-bearing assemblies, radial bearing assemblies,
wire-drawing dies, artificial joints, machining elements, and heat
sinks.
FIG. 6 is an isometric cut-away view of an embodiment of a
thrust-bearing apparatus 600, which may utilize any of the
disclosed PDC embodiments as bearing elements. The thrust-bearing
apparatus 600 includes respective thrust-bearing assemblies 602.
Each thrust-bearing assembly 602 includes an annular support ring
604 that may be fabricated from a material, such as carbon steel,
stainless steel, or another suitable material. Each support ring
604 includes a plurality of recesses (not labeled) that receive a
corresponding bearing element 606. Each bearing element 606 may be
mounted to a corresponding support ring 604 within a corresponding
recess by brazing, press-fitting, using fasteners, or another
suitable mounting technique. One or more, or all of bearing
elements 606 may be configured according to any of the disclosed
PDC embodiments. For example, each bearing element 606 may include
a substrate 608 and a PCD table 610, with the PCD table 610
including a bearing surface 612.
In use, the bearing surfaces 612 of one of the thrust-bearing
assemblies 602 bear against the opposing bearing surfaces 612 of
the other one of the bearing assemblies 602. For example, one of
the thrust-bearing assemblies 602 may be operably coupled to a
shaft to rotate therewith and may be termed a "rotor." The other
one of the thrust-bearing assemblies 602 may be held stationary and
may be termed a "stator."
FIG. 7 is an isometric cut-away view of an embodiment of a radial
bearing apparatus 700, which may utilize any of the disclosed PDC
embodiments as bearing elements. The radial bearing apparatus 700
includes an inner race 702 positioned generally within an outer
race 704. The outer race 704 includes a plurality of bearing
elements 706 affixed thereto that have respective bearing surfaces
708. The inner race 702 also includes a plurality of bearing
elements 710 affixed thereto that have respective bearing surfaces
712. One or more, or all of the bearing elements 706 and 710 may be
configured according to any of the PDC embodiments disclosed
herein. The inner race 702 is positioned generally within the outer
race 704, and thus the inner race 702 and outer race 704 may be
configured so that the bearing surfaces 708 and 712 may at least
partially contact one another and move relative to each other as
the inner race 702 and outer race 704 rotate relative to each other
during use.
The radial bearing apparatus 700 may be employed in a variety of
mechanical applications. For example, so-called "roller-cone"
rotary drill bits may benefit from a radial-bearing apparatus
disclosed herein. More specifically, the inner race 702 may be
mounted to a spindle of a roller cone and the outer race 704 may be
mounted to an inner bore formed within a cone and such an outer
race 704 and inner race 702 may be assembled to form a radial
bearing apparatus.
Referring to FIG. 8, the thrust-bearing apparatus 600 and/or radial
bearing apparatus 700 may be incorporated in a subterranean
drilling system. FIG. 8 is a schematic isometric cut-away view of a
subterranean drilling system 800 that includes at least one of the
thrust-bearing apparatuses 600 shown in FIG. 6 according to another
embodiment. The subterranean drilling system 800 includes a housing
802 enclosing a downhole drilling motor 804 (i.e., a motor,
turbine, or any other device capable of rotating an output shaft)
that is operably connected to an output shaft 806. A first
thrust-bearing apparatus 600.sub.1 (FIG. 6) is operably coupled to
the downhole drilling motor 804. A second thrust-bearing apparatus
600.sub.2 (FIG. 6) is operably coupled to the output shaft 806. A
rotary drill bit 808 configured to engage a subterranean formation
and drill a borehole is connected to the output shaft 806. The
rotary drill bit 808 is shown as a roller-cone bit including a
plurality of roller cones 810. However, other embodiments may
utilize different types of rotary drill bits, such as a so-called
"fixed-cutter" drill bit shown in FIGS. 5A and 5B. As the borehole
is drilled, pipe sections may be connected to the subterranean
drilling system 800 to form a drill string capable of progressively
drilling the borehole to a greater depth within the earth.
A first one of the thrust-bearing assemblies 602 of the
thrust-bearing apparatus 600.sub.1 is configured as a stator that
does not rotate and a second one of the thrust-bearing assemblies
602 of the thrust-bearing apparatus 600.sub.1 is configured as a
rotor that is attached to the output shaft 806 and rotates with the
output shaft 806. The on-bottom thrust generated when the drill bit
808 engages the bottom of the borehole may be carried, at least in
part, by the first thrust-bearing apparatus 600.sub.1. A first one
of the thrust-bearing assemblies 602 of the thrust-bearing
apparatus 600.sub.2 is configured as a stator that does not rotate
and a second one of the thrust-bearing assemblies 602 of the
thrust-bearing apparatus 600.sub.2 is configured as a rotor that is
attached to the output shaft 806 and rotates with the output shaft
806. Fluid flow through the power section of the downhole drilling
motor 804 may cause what is commonly referred to as "off-bottom
thrust," which may be carried, at least in part, by the second
thrust-bearing apparatus 600.sub.2.
In operation, drilling fluid may be circulated through the downhole
drilling motor 804 to generate torque and effect rotation of the
output shaft 806 and the rotary drill bit 808 attached thereto so
that a borehole may be drilled. A portion of the drilling fluid may
also be used to lubricate opposing bearing surfaces of the bearing
elements 606 of the thrust-bearing assemblies 602.
FIG. 9 is a side cross-sectional view of an embodiment of a
wire-drawing die 900 that employs a PDC 902 fabricated in
accordance with the teachings described herein. The PDC 902
includes an inner, annular PCD region 904 comprising any of the PCD
tables described herein that is bonded to an outer cylindrical
substrate 906 that may be made from the same materials as the
substrate 302 shown in FIG. 3A. The PCD region 904 also includes a
die cavity 908 formed therethrough configured for receiving and
shaping a wire being drawn. The wire-drawing die 900 may be encased
in a housing (e.g., a stainless steel housing), which is not shown,
to allow for handling.
In use, a wire 910 of a diameter "d.sub.1" is drawn through die
cavity 908 along a wire-drawing axis 912 to reduce the diameter of
the wire 910 to a reduced diameter "d.sub.2."
While various aspects and embodiments have been disclosed herein,
other aspects and embodiments are contemplated. The various aspects
and embodiments disclosed herein are for purposes of illustration
and are not intended to be limiting. Additionally, the words
"including," "having," and variants thereof (e.g., "includes" and
"has") as used herein, including the claims, shall have the same
meaning as the word "comprising" and variants thereof (e.g.,
"comprise" and "comprises").
* * * * *